Quantum Mechanics in history

Quantum Mechanics is a fundamental branch of physics with wide applications. The foundations of quantum mechanics were established during the first half of the twentieth century by Werner Heisenberg, Max Planck, Louis de Broglie, Albert Einstein, Niels Bohr, Erwin Schrödinger, Max Born, John von Neumann, Paul Dirac, Wolfgang Pauli and others.

The history of quantum mechanics began essentially with the 1838 discovery of cathode rays by Michael Faraday, the 1859 statement of the black body radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig Boltzmann that the energy states of a physical system could be discrete, and the 1900 quantum hypothesis by Max Planck that any energy is radiated and absorbed in quantities.

On 19 October 1900 the Berliner Max Planck at age 42 announced a formula that fit the experimental result perfectly, yet he had no explanation for the formula – it just happened to fit.

He worked to find an explanations through the late fall and finally was able to derive his formula by assuming that the atomic jigglers could not take in any possible energy, but only certain special ‘allowed’ values. He announced the result ion 14 December 1900 and this date is now considered the birthday of quantum mechanics.

According to the theorem proved by Gustav Kirchhoff in 1859 on the basis of the second principle of thermodynamics, the blackbody spectrum has a very remarkable property: It is a universal function of temperature only. In the 1877, Ludwig Boltzmann and Willy Wien restricted the form of this function by combining electromagnetism and thermodynamics.

In 1905, Einstein computed the entropy of dilute thermal radiation from the high frequency limit of Planck’s law.

In 1913, Niels Bohr emphasized that mathematical symbols from classical mechanics permitted visualization of the atom as a minuscule Copernican system. Although suitably quantized laws of classical mechanics are used to calculate the electron’s allowed orbits, or stationary states, classical mechanics can neither depict nor describe the electron in transit.

Arnold Sommerfeld and others extended the Bohr model with considerable but incomplete success. In1925, the first form of quantum mechanics, was invented by 23 year-old Heisenberg, which soon became known as ‘matrix mechanics’. Heisenberg focused attention on an ‘observable’ set of quantum amplitudes, each depending on not one but two stationary phase.

In 1932 von Neumann put quantum theory on a firm theoretical basis. Some of the earlier work had lacked mathematical rigour, but von Neumann put the whole theory into the setting of operator algebra.

In 1933 Fermi develops a successful quantum field theory of beta decay. It describes how neutrons spontaneously change into protons and emit electrons and neutrinos.
Quantum Mechanics in history